The present invention generally relates to a trailer hitch coupler and more particularly relates to a trailer hitch coupler of the type that includes a vertically movable pin for engaging a drawbar eye on a trailer.
Trailer hitch couplers that include a pin that is normally held in place by gravity and some type of retaining mechanism such as a D-ring clip or a spring have been utilized in the industry. These types of hitch couplers are often used, for example, on airport ground equipment to pull various other equipment, such as baggage carts and the like. FIG. 11 illustrates a prior art hitch coupler 100 that includes a frame 111 and a pin 130 having a handle 140 disposed at its upper end. The frame 111 includes a back plate 112 functioning as the mounting plate for mounting the frame to either the rear of the towing vehicle or the front of the towed vehicle. The frame 111 further includes a top horizontal plate 114, a middle horizontal plate 116, and a bottom horizontal plate 118. The middle horizontal plate 116 and the bottom horizontal plate 118 are preferably dimensioned so as to allow the receipt of a drawbar eye 150 therebetween. The middle plate 116 and the bottom plate 118 define a throat 125 for receiving the drawbar eye 150. The pin 130 is configured to slide vertically within the horizontal extending plates 114, 116, and 118. The pin 130 includes a horizontal bar 132 that limits the downward travel of the pin 130 relative to the frame 111 while also cooperating with a washer 134 to provide a biasing surface for the pin 130 relative to a cylindrical spring 136, which extends between the washer 134 and a bottom surface of the upper horizontal plate 114 of the frame 111. The cylindrical spring 136 applies pressure against the washer 134 to bias the pin 130 into an extended, coupled position through the drawbar eye 150. The washer 134 includes a slot 190 that allows the washer 134 to pass by a flange plate 192 extending from the back plate 112. When the pin 130 is in a retracted position, the handle 140 is rotated to move the slot 190 out of alignment with the flange plate 192, thereby resting a bottom surface of the washer 134 on a top of the flange plate 192 to maintain the pin in the retracted position.
However, normal compression springs require a tall hitch frame. Additionally, retaining mechanisms such as the flange/slotted washer, are either not used or are mounted outside the spring between the spring and the frame where it is not easily visible to the user. These types of hitch couplers are generally fairly large and heavy relative to the load that is applied.
Accordingly, there exists a need for a coupling assembly that is more user friendly, compact, stronger, and lighter than prior couplers of a similar nature.